<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script src="https://cdn.jsdelivr.net/npm/vue@2"></script>
		<style>
			body {
				display: flex;
				flex-direction: column;
				align-items: center;
			}

			input {
				font-size: 20px;
				color: red;
			}
		</style>
	</head>
	<body>
		<div id="app">
			<input type="text" v-model.number="num1">
			<input type="text" v-model.number="num2">
			<button>=</button>
			<input type="text" v-model.number="getSum">

		</div>
		    
		<script>
			var exam = new Vue({
				el: "#app",
				data: {
					num1: '',
					num2: '',
				},
				computed: {
					getSum: function() {
						return this.num1 + this.num2
					}
				}
			})
		</script>    
	</body>
</html>
